This paper covers the efffect of the grain microstructure (ferrite/austenite ratio and grain size) ofDuplex Stainless Steels (DSS) and thePitting Resistance of these alloys in chloride containing solutions. Particular attention will be given to the effect of themicrostructure of the steel on the Critical Pitting Temperature andPitting Potential. Tests with samples annealed for longer period of times to increase the grain size of both ferrite and austenite on commercially available 25Cr DSS have shon that result on the increase of the CPT in chloride containing solutions.